1. Field of the Invention
The present invention relates to the field of image processing, particularly relates to the field of image division, and more particularly related to a method of detecting a screen area in a captured image as well as a system using the method.
2. Description of the Related Art
In various meetings, it is very helpful to use a projector as an assistant tool for a presentation. However, during the presentation, a presenter needs to frequently operate a computer to switch contents needing to be projected on a screen, or needs to let an assistant switch the contents projected on the screen by operating a computer connected to the projector according to presentation speed of the presenter. This kind of method of using the projector brings ultra-convenience to the presenter, but its operation still costs time or work.
As a result, a method able to operate a computer by directly clicking contents on a screen has been proposed; that is, an image including a screen area is captured by an image capture device, then positional information of the screen area in the captured image is extracted by the computer, and then the contents needing to be projected on the screen are switched by utilizing the positional information of the screen area and operations carried out with regard to the contents on the screen.
In order to extract a specific area from a captured image, US Patent Application Publication NO. 2004/0165786A discloses a method and a device for extracting whiteboard contents in an image and converting the extracted whiteboard contents into an electronic document. In order to be able to automatically recognize a whiteboard area in the captured image, this patent application adopts a rectangle detection algorithm for recognizing the whiteboard area. However, according to the method described in the patent application, plural parallel straight lines are usually detected when carrying out whiteboard side detection; as a result, it is very difficult to accurately determine which one of the straight lines is the whiteboard side. This results in a big error between the detected whiteboard and the actual whiteboard.
Furthermore US Patent Application Publication NO. 2008/0266253A discloses a system by which light spots projected on a screen area by a computer are tracked. In the system described in this patent application, a screen area detection method is adopted. This method captures an image by using an image capture device, then carries out binary processing with regard to the captured image, and then sorts out a rectangle from the processed image so as to obtain the screen area. However, this method depends on the quality of the captured image very much; as a result, in order to improve the quality of the captured image, it is necessary to add a special filter for the image capture device.
Furthermore, in U.S. Pat. No. 6,618,076, a device used in a calibration projector-camera system is disclosed. The technical proposal described in this patent carries out feature extraction by letting a projector project a special pattern on a screen.
Therefore a method and a device, by which a screen area may be detected more accurately in a case where hardware is not added so that a presenter is able to switch contents more accurately when operating a projecting system, are desirable.